(1) First of all, it is important for comprehension and control of the friction and lubrication on solid surfaces and orientation and structuration of liquid molecules and liquid crystal molecules to know a shear response of a sample (such as liquid and liquid crystal) sandwiched between the solid surfaces along with change of film thickness in nanometer scale. The resonance shear measurement for measuring the shear response of a sample is a method to provide a shear by oscillating a surface on one side of a sample horizontally and to monitor its response near a resonance frequency. Plotting the shear response as a function of frequency gives a resonance curve. Resonance frequency and a resonance peak height are sensitive to the properties of the sample between the solid surfaces and immune to an oscillation noise from outside of the measurement apparatus.
The conventional method to measure precisely the shear response of a sample sandwiched between solid surfaces is to measure the shear response of the sample to a shear while changing frequency around the resonance frequency and to plot the response as a function of frequency to obtain a resonance shear curve. This method is disclosed in Non-Patent Document 1 shown below.
An apparatus for precise measurement of shear stress was proposed by the present inventors as described in Patent Document 1 below.
(2) Secondly, the present inventors have proposed an apparatus for precise measurement of shear stress capable of measuring with high accuracy a rheological behavior in an ultra small space with a nano-scale dimension, as described in Patent Document 2.
The present inventors have also proposed a surface force measurement apparatus and method capable of measuring a surface force between samples with high accuracy even if the samples are not transparent for light, as described in Patent Document 3 below.
[Patent Document 1] Japanese Patent Publication No. 3032152
[Patent Document 2] Japanese Patent Publication No. 3032152
[Patent Document 3] Japanese Patent Application Publication No. 2001-108603
[Non-Patent Document 1] Liquid Crystal, vol. 6, No. 1, pp. 34-41, 2002.